Hey, an idea for the DERP.
I'm not sure exactly how to quantify everything, but I figure a monthly or weekly scoreboard for DERPs in addition to the win streak metric as its own separate thing would be nice.
For example, each badge can have its own point value. Blanking out preps could have a score value (either small compared to Purist or not stacking with Purist, if applicable). If it's weekly, you probably wouldn't need bonus points for low-winrate maps, since just getting the win itself would be a significant reward.
Maybe a win is worth, say, 100 base points. Cheeky, 5 points. Parched, 10 or 15. 5 or 10 points per skipped prep, or instead 50 for Purist. 5-10 for Ding Max, Faithless, Unstoppable. 10-20 for Warmonger, 5-10 for Specialist. 5 points per level below 8 at the finish. Maybe even have a "preferred badge" prep worth an extra 10 points, whatever the badge is.
I'm not sure how the point values should be balanced, but I know lots of people (not me especially) like to stretch for badges on easier maps as it is.